Enhancing Crystallization in Hybrid Perovskite Solar Cells Using Thermally Conductive 2D Boron Nitride Nanosheet Additive.

Controlling crystallization and grain growth is crucial for realizing highly efficient hybrid perovskite solar cells (PSCs). In this work, enhanced PSC photovoltaic performance and stability by accelerating perovskite crystallization and grain growth via 2D hexagonal boron nitride (hBN) nanosheet additives incorporated into the active perovskite layer are demonstrated. In situ X-ray scattering and infrared thermal imaging during the perovskite annealing process revealed the highly thermally conductive hBN nanosheets promoted the phase conversion and grain growth in the perovskite layer by facilitating a more rapid and spatially uniform temperature rise within the perovskite film. Complementary structural, physicochemical, and electrical characterizations further showed that the hBN nanosheets formed a physical barrier at the perovskite grain boundaries and the interfaces with charge transport layers, passivating defects, and retarding ion migration. As a result, the power conversion efficiency of the PSC is improved from 17.4% to 19.8%, along with enhanced device stability, retaining ≈90% of the initial efficiency even after 500 h ambient air storage. The results not only highlight 2D hBN as an effective additive for PSCs but also suggest enhanced thermal transport as one of the pathways for improved PSC performance by 2D material additives in general.

Synthesis of an Effective Flame-Retardant Hydrogel for Skin Protection Using Xanthan Gum and Resorcinol Bis(diphenyl phosphate)-Coated Starch.

We report on the production of a flame-resistant xanthan gum (XG)-based hydrogel formulation, which could be directly applied onto the skin for protection against burning projectiles. The hydrogel cream represents an efficient use of XG and starch, both of which are biodegradable, reusable natural materials and are also GRAS-certified. The flame-retardant agent resorcinol bis(diphenyl phosphate) (RDP) was shown to be nontoxic to cells in vitro when adsorbed directly onto the starch delivery vehicle. Three hydrogel formulations were studied, the pure XG hydrogel, commercial FireIce hydrogel, and RDP-XG/RDP-starch hydrogel. After application of a direct flame for 150 s, the RDP-XG/RDP-starch hydrogel produced a thick char layer, which was easily removed, showing undamaged chicken skin and tissue underneath. In contrast, complete burning of skin and tissue was observed on untreated control samples and those covered with FireIce and pure XG hydrogels. The thermal protective performance test was also performed, where the heat transfer was measured as a function of time for all three hydrogels. The RDP-XG/RDP-starch hydrogel was able to prolong the protection time before obtaining a second-degree burn for 103 s, which is double that for FireIce and triple that for the pure XG hydrogel. The model proposed involves endothermic reactions, producing char and burning "cold", as opposed to simply relying on the adsorbed water in the hydrogel for burn protection.

Disparities in overall survival by varying duration of disability in activities of daily living in older people: A population-based cohort from Chinese Longitudinal Healthy Longevity Survey (CLHLS).

OBJECTIVES: To investigate the association between duration of disability in activity of daily living (ADL) and overall survival in older individuals. DESIGN: A prospective cohort study. SETTING: Community-based data from Chinese Longitudinal Healthy Longevity Survey. PARTICIPANTS: In total, 13,560 participants without ADL disability and 2772 participants with ADL disability at baseline were included. MEASUREMENTS: ADL disability was assessed using Katz index scale, which included six essential ADLs: dressing, bathing, transferring, toileting, continence, and eating. Dependence of each item was scored on a scale of 1, the maximum total score was 6. At baseline, duration of ADL disability was defined as the maximum duration among the six items. The study outcome was overall survival. Accelerated failure time models were constructed to investigate the association between duration of ADL disability and overall survival. Subgroup analyses by sex, age, and multimorbidites, as well as sensitive analyses were conducted. RESULTS: During 81,868.7 person-years follow-up, 11,092 deaths were recorded. Overall, ADL disability was associated with lower overall survival compared to non-ADL disability. With duration of ADL disability extending, the overall survival strikingly dropped in the first 12 months, reaching its lowest point with adjusted time ratio (TR) at 0.66 (95%CI: 0.61-0.72, p < 0.001), then moderately grew until the 60th month, finally stayed constant thereafter. Participants with ADL scores of 1-3 had higher survival compared to those with scores of 4-6, and both groups followed a similar trend of varied survival to the whole cohort. Moreover, subgroup analyses and sensitivity analyses showed the robustness of these findings. CONCLUSIONS: Our findings first address a golden time window for the older individuals with ADL disability. More attention should be given to them, especially in the first 12 months since diagnosis, to reduce mortality and extend the lifespan.

Association of dietary live microbe intake with abdominal aortic calcification in US adults: a cross-sectional study of NHANES 2013-2014.

Object: To explore the potential association between dietary live microbe intake and abdominal aortic calcification (AAC). Methods: We conducted a cross-section study based on the National Health and Nutrition Examination Survey (NHANES). We categorized the participants into three groups (low, medium, and high dietary intake of live microbes) according to Sanders's dietary live microbe classification system and participants' 24-h dietary recall data. AAC was quantified by using dual-energy X-ray absorptiometry (DXA) and diagnosed by using the Kauppila AAC-24 score system. The analyses utilized weighted logistic regression and weighted linear regression. Results: A total of 2,586 participants were included. After the full adjustment for covariates, compared to participants with a low dietary live microbe intake, participants with a high dietary live microbe intake had a significantly lower risk of severe AAC (OR: 0.39, 95% CI: 0.22, 0.68, p = 0.003), and the AAC score was also significantly decreased (ß:-0.53, 95% CI: -0.83, -0.23, p = 0.002). Conclusion: In this study, more dietary live microbial intake was associated with lower AAC scores and a lower risk of severe AAC. However, more research is needed to verify this.

Signaling pathways in vascular function and hypertension: molecular mechanisms and therapeutic interventions.

Hypertension is a global public health issue and the leading cause of premature death in humans. Despite more than a century of research, hypertension remains difficult to cure due to its complex mechanisms involving multiple interactive factors and our limited understanding of it. Hypertension is a condition that is named after its clinical features. Vascular function is a factor that affects blood pressure directly, and it is a main strategy for clinically controlling BP to regulate constriction/relaxation function of blood vessels. Vascular elasticity, caliber, and reactivity are all characteristic indicators reflecting vascular function. Blood vessels are composed of three distinct layers, out of which the endothelial cells in intima and the smooth muscle cells in media are the main performers of vascular function. The alterations in signaling pathways in these cells are the key molecular mechanisms underlying vascular dysfunction and hypertension development. In this manuscript, we will comprehensively review the signaling pathways involved in vascular function regulation and hypertension progression, including calcium pathway, NO-NOsGC-cGMP pathway, various vascular remodeling pathways and some important upstream pathways such as renin-angiotensin-aldosterone system, oxidative stress-related signaling pathway, immunity/inflammation pathway, etc. Meanwhile, we will also summarize the treatment methods of hypertension that targets vascular function regulation and discuss the possibility of these signaling pathways being applied to clinical work.

Proximal aorta dilatation in hypertension.

Dilation of the proximal aorta is a common clinical manifestation in hypertensive patients. Although it is straightforward to link hypertension with proximal aortic dilation, previous studies on their interrelation have yielded controversial results. Cross-sectional design, methodology of blood pressure assessment, confounding factors like medications, and inconsistent reference values may lead to the paradoxical conclusions. Recently, advances have been made in the exploration of determinants and clinical value of proximal aortic dilatation. Thus, we reviewed these findings and summarized that aortic dilatation may be the consequence of hemodynamic and nonhemodynamic co-factors' combined action. Moreover, proximal aortic dilatation tends to be a predictor for aortic aneurysm dissection or rupture, hypertensive target organ damage as well as cardiovascular events. The present review contributes to a comprehensive understanding of the pathological process of proximal aortic dilatation in hypertension.

Melt extrusion deposition (MED™) 3D printing technology - A paradigm shift in design and development of modified release drug products.

Three-dimensional printing (3DP) technology offers unique advantages for pharmaceutical applications. However, most of current 3D printing methods and instrumentations are not specifically designed and developed for pharmaceutical applications. To meet the needs in pharmaceutical applications for precision, compatibility with a wide range of pharmaceutical excipients and drug materials without additional processing, high throughput and GMP compliance, an extrusion-based 3D printer based on Melt Extrusion Deposition (MED™) 3D printing technology was developed in this study. This technology can process powder pharmaceutical excipients and drugs directly without the need of preparing filament as required by FDM 3D printing. Six different tablet designs based on compartment models were used to demonstrate the precision and reproducibility of this technology. The designed tablets were fabricated using the GMP-compliant MED™ 3D printer and were evaluated in vitro for drug release and in vivo for selected designs using male beagle dogs. Tablet designs with one or more compartments showed versatile release characteristics in modulating the release onset time, release kinetics, duration of release and mode of release. Multiple drugs or formulations were fabricated into a single tablet to achieve independent release kinetics for each drug or to fine-tune the pharmacokinetic profile of a drug. Building upon the theoretical analysis of models, precision and reproducibility of MED™ 3D printing technology, a novel product development approach, 3D printing formulation by design (3DPFbD®) was developed to provide an efficient tool for fast and efficient pharmaceutical product development. The MED™ 3D printing represents a novel and promising technology platform encompassing design and development of modified drug release products and has potential to impact the drug delivery and pharmaceutical product development.

Recent advances in polymer-based drug delivery systems for local anesthetics.

Local anesthetics, which cause temporary loss of pain by inhibiting the transmission of nerve impulses, have been widely used in clinical practice. However, neurotoxicity and short half-lives have significantly limited their clinical applications. To overcome those barriers, numerous drug delivery systems (DDS) have been designed to encapsulate local anesthetic agents, so that large doses can be released slowly and provide analgesia over a prolonged period. So far, multiple classes of local anesthetic carriers have been investigated, with some of them already on the market. Among those, polymer-based delivery platforms are the most extensively explored, especially in the form of polymeric nanoparticle carriers. This review gives a specific focus on the most commonly used natural and synthetic polymers for local anesthetics delivery, owing to their excellent biocompatibility, biodegradability and versatility. State-of-the-art studies concerning such polymer delivery systems have been discussed in depth. We also highlight the impact of those delivery platforms as well as some key challenges that need to be overcome for their broader clinical applications. STATEMENT OF SIGNIFICANCE: Currently, local anesthetics have been widely used in clinically practices to prevent transmission of nerve impulses. However, the applications of anesthetics are greatly limited due to their neurotoxicity and short half-lives. Moreover, it is difficult to maintain frequent administrations which can cause poor compliance and serious consequences. Numerous drug delivery systems have been developed to solve those issues. In this review, we highlight the recent advances in polymer-based drug delivery systems for local anesthetics. The advantages as well as shortcomings for different types of polymer-based drug delivery systems are summarized in this paper. In the end, we also give prospects for future development of polymer drug delivery systems for anesthetics.

Templated dentin formation by dental pulp stem cells on banded collagen bundles nucleated on electrospun poly (4-vinyl pyridine) fibers in vitro.

Eventhough it is well established that materials can promote stem cell differentiation, hard tissue formation is a templated process for which little is known regarding the in vitro process. We have found that surface curvature enables self-assembly of triple helical collagen fibrils into banded bundle structures from rat tail and human collagen secreted by dental pulp stem cells. Collagen fibrils were adsorbed at 4 °C on spun cast flat P4VP films and electrospun fibers. Protein adsorption was observed on both surfaces, but large banded bundles with a uniform spacing of approximately 55 nm were present only on the fiber surfaces. SEM/EDS mapping showed that dental pulp stem cells plated on the same surfaces biomineralized copiously only along the electrospun fibers. Raman spectroscopy indicated that despite the presence of adsorbed collagen on the flat surfaces, only the deposits present on the fibrous surface had a protein to hydroxyl apatite ratio similar to natural dentin from human teeth. RT-PCR indicated up regulation of collagen, osteocalcin and dental sialophosphate protein, confirming that odontogenic differentiation is promoted only on the fiber scaffolds. Taken together the results indicate that, in addition to surface chemistry, the supermolecular structure of ECM collagen, which is essential in directing DPSCs differentiation and templating biomineralization, can be modified by the underlying surface morphology. STATEMENT OF SIGNIFICANCE: The past decade has been focused efforts in the use of dental pulp stem cells (DPSC) for dental regeneration. Eventhough the factors required for DPSCs differentiation have been well studied, actual mineral deposition, positively identified as dentin, has not been achieved in vitro. Hard tissue is known to be a templated process in vivo where the mineral to protein ratio is tightly controlled via proteins which aid in collagen conformation and mineral sequestration. Here we show that one can mimic this process in vitro via the combination of materials selection and morphology. The material chemistry is shown to induce genetic upregulation the genes responsible for collagen and osteocalcin, while Raman spectroscopy confirms the translation and adsorption the proteins on the substrate. But, we show that the simple presence of collagen is not enough to template actual biomineral deposition similar to that found in vivo. Mineral deposition is a complicated process templated on collagen bundles and mediated by specific sibling proteins that determine the protein to mineral ratio. Here we show that surface curvature can reduce the barrier to collagen bundle formation, directing DPSC differentiation along odontogenic lineage, and subsequently templating actual dentin, comparable to that found in vivo in human teeth.

Enhancing the Mechanical Properties of Biodegradable Polymer Blends Using Tubular Nanoparticle Stitching of the Interfaces.

"Green" polymer nanocomposites were made by melt blending biodegradable poly(lactic acid) (PLA) and poly(butylene adipate-co-butylene terephthalate) (PBAT) with either montmorillonite clays (Cloisite Na(+)), halloysite nanotubes (HNTs), the resorcinol diphenyl phosphate (RDP)-coated Cloisite Na(+), and coated HNTs. A technique for measuring the work of adhesion (Wa) between nanoparticles and their matrixes was used to determine the dispersion preference of the nanoparticles in the PLA/PBAT blend system. Transmission electron microscopy (TEM) images of thin sections indicated that even though both RDP-coated nanotubes and clay platelets segregated to the interfacial regions between the two immiscible polymers, only the platelets, having the larger specific surface area, were able to reduce the PBAT domain sizes. The ability of clay platelets to partially compatibilize the blend was further confirmed by the dynamic mechanical analysis (DMA) which showed that the glass transition temperatures of two polymers tended to shift closer. No shift was observed with either coated or uncoated HNTs samples. Izod impact testing demonstrated that the rubbery PBAT phase greatly increased the impact strength of the unfilled blend, but addition of only 5% of treated clay decreased the impact strength by nearly 50%. On the other hand, an increase of 9% relative to the unfilled blend sample was observed with the addition of 5% treated nanotubes. TEM cross-section analysis confirmed that the RDP-coated clay platelets covered most of the interfacial area. On one hand, this enabled them to reduce the interfacial tension effectively; on the other hand, it prevented chain entanglements across the phase boundary and increased the overall brittleness, which was confirmed by rheology measurements. In contrast, the RDP-coated HNTs were observed to lie perpendicular to the interface, which made them less effective in reducing interfacial tension but encouraged interfacial entanglements across the interface, resulting in "stitching" of the interface and an increase in the Izod impact of the blend.